Non-compliant medical balloon

ABSTRACT

A non-compliant fiber-reinforced medical balloon comprises a first fiber layer and a second fiber layer embedded in a continuous matrix of thermally-weldable polymer material defining a barrel wall, cone walls and neck walls. The fibers of the first fiber layer run substantially parallel to one another and substantially parallel to the longitudinal axis. The fibers of the first fiber layer have a pattern of different lengths and are divisible into a first group and a second group based on length.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.12/537,850, filed on Aug. 7, 2007, which is a continuation of U.S.patent application Ser. No. 12/187,259, filed on Aug. 6, 2008 andentitled, “NON-COMPLIANT MEDICAL BALLOON,” which claims priority to U.S.Provisional Application Ser. No. 60/954,252, filed on Aug. 6, 2007, andentitled “NON-COMPLIANT MEDICAL BALLOON,” the specifications of whichare incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to the field of medical balloons. In particular,it relates to non-compliant medical balloons that are useful inangioplasty and other medical applications including cardiology,radiology, urology and orthopedics.

BACKGROUND

Non-compliant medical balloons for performing angioplasty and othermedical procedures are known. U.S. Pat. No. 6,746,425 to Beckhamdiscloses a non-compliant medical balloon and methods for manufacturingthe balloon. U.S. Patent Application Publication No. US 2006/0085022 toHayes et al. discloses a non-compliant medical balloon having anintegral woven fabric layer and methods for manufacturing the balloon.U.S. Patent Application Publication No. US 2006/0085023 to Davies, Jr.et al. discloses a medical balloon having strengthening rods and methodsfor manufacturing the balloon. U.S. Patent Application Publication No.US 2006/0085024 to Pepper et al. discloses a non-compliant medicalballoon having an integral non-woven fabric layer and methods formanufacturing the balloon. U.S. Pat. No. 6,746,425 and Publication Nos.US 2006/0085022, US 2006/0085023 and US 2006/0085024 are herebyincorporated herein by reference.

It is desirable to make the outer wall of a non-compliant medicalballoon as thin as possible while still maintaining the requiredpressure rating or burst strength. In non-compliant balloons, the wallstypically forms pleats when deflated (i.e., before or after inflation),and these pleats are folded over, wrapped and/or rolled around the longaxis of the balloon. The thinner the wall material, the smaller thediameter of the deflated balloon. This smaller diameter facilitatespassage of the deflated balloon through narrow vessels, lumens orcavities of the body prior to deployment. The walls of conventionalnon-compliant balloons include numerous discrete layers and/orcomponents that tend to increase the thickness. A need therefore existsfor a medical balloon having thinner walls and/or walls with fewerlayers or components.

It is also desirable to make the outer wall of a non-compliant medicalballoon as flexible as possible while still maintaining the requiredpressure rating or burst strength. The flexibility of the deflatedballoon directly affects its “trackability,” i.e., its ability totraverse sharp turns or branches of the vessels or body cavities throughwhich the balloon must pass. The more flexible the walls, the better thetrackability. The walls of conventional balloons often include physicaladhesive layers needed to hold the disparate layers together or toprevent the movement of the wall components relative to one another.Unfortunately, the adhesives, e.g., polyurethanes, used are frequentlystiffer than the materials/components being joined. Thus, these adhesivelayers may undesirably increase the stiffness of the balloon walls. Aneed therefore exists for a medical balloon that eliminates or reducesthe presence of adhesives in the finished balloon.

Conventional non-compliant balloons may have a wall thickness thatvaries considerably at different points of the balloon. For example, thewall thickness of the neck portion may be significantly thicker than thewall thickness of the barrel portion. Further; the wall thickness of thecone portion may vary from a relatively large thickness proximate theneck portion to a relatively low thickness proximate the barrel portion.This variation in wall thickness is frequently caused by theincorporation of blow-molded components (which have inherent wallthickness variability) into the structure of the balloon, but may becaused by other factors as well. Regardless of the cause, thicker wallsin portions of the balloon that must be folded tend to affect adverselythe user's ability to fold the deflated balloon into the desireddiameter. This effect may be especially significant in the cone portion,where thicker cone walls can result in “bulges” at the front and theback of the folded balloon that are larger than the intervening barrelportion and, thus, force the user the increase the size of theintroducer used to insert the balloon into the patient. It is thusdesirable to develop non-compliant balloon construction methods yieldingbetter control over the wall thickness of the balloon at all portions ofthe envelope. It is further desirable to make non-complaint medicalballoons having relatively uniform wall thickness for the entireenvelope, including the barrel, cone and neck portions.

It is still further desirable to simplify the construction ofnon-compliant medical balloons so as to reduce the amount of time andlabor required for manufacture, to reduce the product defect rate,and/or to reduce the cost of production. The conventional constructionof non-compliant balloons may require many discrete steps, some or allof which may require precision hand assembly that can be difficult orexpensive to automate. A need therefore exists for improved methods ofmanufacturing non-compliant medical balloons.

SUMMARY

In one aspect thereof, there is disclosed a non-compliantfiber-reinforced medical balloon that may be inflated and deflated, andwhen inflated exhibits minimal change in radial distension across apredetermined range of internal pressures. The balloon has a generallycylindrical barrel wall disposed between tapered cone walls andcylindrical neck walls extending therefrom along a longitudinal axis.The balloon comprises a first fiber layer and a second fiber layerembedded in a continuous matrix of thermally-weldable polymer materialdefining a barrel wall, cone walls and neck walls. The fibers of thefirst fiber layer run substantially parallel to one another andsubstantially parallel to the longitudinal axis of the balloon. Thefibers of the first fiber layer have a pattern of different lengths andare divisible into a first group and a second group based on length.Each fiber of the first group begins in the neck wall at one end of theballoon, extends continuously in the longitudinal direction andterminates in the neck wall at the opposite end of the balloon.Substantially all of the fibers of the first group have a generallyuniform length. Each fiber of the second group begins in the cone wallat one end of the balloon, extends continuously in the longitudinaldirection and terminates in the cone wall at the opposite end of theballoon. The length of the fibers of the second group variesprogressively in accordance to their proximity to the fibers of thefirst group. The fibers of the second group closest to the fibers of thefirst group are longer than the fibers of the second group further fromthe fibers of the first group. The fiber of the second fiber layer windscircumferentially around the longitudinal axis of the balloonsubstantially over the entire length of the balloon including the neckwalls, the cone walls and the barrel wall.

In another aspect thereof, there is disclosed a non-compliant medicalballoon that may be inflated and deflated, and when inflated exhibitsminimal change in radial distension across a predetermined range ofinternal pressures. The balloon has a generally cylindrical barrel walldisposed between tapered cone walls and cylindrical neck walls extendingtherefrom along a longitudinal axis. The balloon comprises an innerlayer of thermally-weldable polymer material, a first fiber/polymermatrix layer disposed over the inner layer, a second fiber/polymermatrix layer disposed over the first fiber/polymer matrix layer, and anouter layer of thermally-weldable polymer material disposed over thesecond fiber/polymer matrix layer. The fibers of the first fiber/polymermatrix layer are substantially inelastic and run substantially parallelto one another and substantially parallel to the longitudinal axis ofthe balloon. The polymer of the first fiber/polymer matrix layer is athermally-weldable polymer material. The fibers of the secondfiber/polymer matrix layer are substantially inelastic and windcircumferentially around the longitudinal axis of the balloonsubstantially over the entire length of the balloon. The polymer of thesecond fiber/polymer matrix layer is a thermally-weldable polymermaterial. All of the thermally-weldable polymer materials from each ofthe layers have been fused together into a continuous polymer matrixencapsulating the fibers of the first and second fiber/polymer matrixlayers and defining a barrel wall, cone walls and neck walls.

In another aspect, a method of making non-compliant fiber-reinforcedmedical balloon is disclosed. The method includes the steps of: (1)embedding a first fiber layer in a continuous matrix ofthermally-weldable polymer, (2) cutting the first fiber layer in apattern defining the generally cylindrical barrel wall, tapered conewalls and cylindrical neck walls wherein the fibers of the first fiberlayer extend substantially parallel to the longitudinal axis of theballoon, and (3) wrapping the fiber of the second fiber layercircumferentially around the longitudinal axis of the balloonsubstantially over the entire length of the balloon including the neckwalls, the cone walls and the barrel wall. In one embodiment, the fibersof the first fiber layer have a pattern of different lengths and aredivisible into a first group and a second group based on length. Thefibers of the first group begin in the neck wall at one end of theballoon, and extend continuously in the longitudinal direction andterminate in the neck wall at the opposite end of the balloon. The fiberof the second group begins in the cone wall at one end of the balloonand extends continuously in the longitudinal direction and terminatingin the cone wall at the opposite end of the balloon. The length of thefibers of the second group vary progressively in accordance to theirproximity to the fibers of the first group with the fibers of the secondgroup closest to the fibers of the first group being longer than thefibers of the second group further from the fibers of the first group.In one variation, the first fiber layer is affixed over a mandrel beforewrapping the fiber of the second fiber layer around the balloon. Themethod may further include embedding the second fiber layer in thecontinuous matrix of thermally-weldable polymer.

In yet another aspect, a non-compliant fiber-reinforced medical balloonthat may be inflated and deflated, and when inflated exhibits minimalchange in radial distension across a predetermined range of internalpressures includes a generally cylindrical barrel wall disposed betweentapered cone walls and cylindrical neck walls extending therefrom alonga longitudinal axis. The balloon includes a first textile layercomprising a plurality of substantially inelastic fibers embedded in acontinuous matrix of thermally-weldable polymer material defining abarrel wall, cone walls and neck walls. The first textile layer may beone of a woven, knitted, braided or non-woven textile material. Theballoon further includes a fiber layer wherein the fiber windscircumferentially around the longitudinal axis of the balloonsubstantially over the entire length of the balloon including the neckwalls, the cone walls and the barrel wall, in one variation, the balloonincludes an outer layer of thermally-weldable polymer material disposedover the second textile layer. The thermally-weldable polymer materialsfrom each of the layers may be fused together into a continuous polymermatrix encapsulating the fibers of the first and second fiber/polymermatrix layers and defining the barrel wall, cone walls and neck walls.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding, reference is now made to thefollowing description taken in conjunction with the accompanyingDrawings in which:

FIG. 1 is a side view of a medical balloon in accordance with oneembodiment;

FIG. 2 is a cross-sectional side view of the medical balloon of FIG. 1;

FIG. 2A is an enlarged cross-sectional view of the balloon wall lookingin the circumferential direction taken along line 2A-2A of FIG. 2;

FIG. 2B is an enlarged cross-sectional view of the balloon wall lookingin the longitudinal direction taken along line 2B-2B of FIG. 2;

FIG. 3 a side view of a raw mandrel tube prior to blow-molding;

FIG. 4 shows the mandrel tube of FIG. 3 fitted with a polymer sleeveprior to blow-molding;

FIG. 5 shows the removable mandrel with conformal layer afterblow-molding;

FIG. 5A is an enlarged cross-sectional view of the in-progress balloonwall overlying the mandrel looking in the circumferential directiontaken along line 5A-5A of FIG. 5;

FIG. 5B is an enlarged cross-sectional view of the in-progress balloonwall overlying the mandrel looking in the longitudinal direction takenalong line 5B-5B of FIG. 5;

FIG. 6 is a cross-sectional end view of a tow of inelastic fibermaterial prior to flattening;

FIG. 7 is a cross-sectional end view of a flattened tow of inelasticfiber material used as a reinforcing fiber in some embodiments;

FIG. 8 illustrates forming flattened reinforcing fibers and preparingfiber-reinforced polymer sheets in accordance with additionalembodiments;

FIG. 9 illustrates coating the reinforcing fibers with polymer materialduring preparation of fiber-reinforced polymer sheets in accordance withadditional embodiments;

FIG. 10 illustrates removing sheets of polymer embedded with reinforcingfibers during preparation of fiber-reinforced polymer sheets inaccordance with additional embodiments;

FIG. 11 illustrates fusing and flattening fiber-reinforced polymersheets in accordance with additional embodiments;

FIG. 12 illustrates patterning and cutting a pre-fabricatedfiber-reinforced balloon wall layer (also called a “sock”) in accordancewith additional embodiments;

FIG. 13 shows a perspective view of a patterned sock, i.e., aprefabricated fiber-reinforced balloon wall layer, in accordance withadditional embodiments;

FIG. 13A shows an enlarged view of a portion of the patterned sock ofFIG. 13 to better illustrate the pattern of the reinforcing fibers;

FIG. 13B shows an enlarged view of a portion of sock sheet similar tothe sock of FIG. 13, but incorporating woven textile reinforcement inaccordance with an alternate embodiment;

FIG. 13C shows an enlarged view of a portion of sock sheet similar tothe sock of FIG. 13, but incorporating braided textile reinforcement inaccordance with an alternate embodiment;

FIG. 13D shows an enlarged view of a portion of sock sheet similar tothe sock of FIG. 13, but incorporating knitted textile reinforcement inaccordance with an alternate embodiment;

FIG. 13E shows an enlarged view of a portion of sock sheet similar tothe sock of FIG. 13, but incorporating non-woven textile reinforcementin accordance with an alternate embodiment;

FIG. 13F shows a portion of a patterned sock including multiple textilereinforcement layers in accordance with another embodiment;

FIG. 14 illustrates affixing a patterned sock over the in-progressballoon and mandrel in accordance with additional embodiments;

FIG. 14A is an enlarged cross-sectional view of the in-progress balloonwall overlying the mandrel looking in the circumferential directiontaken along line 14A-14A of FIG. 14;

FIG. 14B is an enlarged cross-sectional view of the in-progress balloonwall overlying the mandrel looking in the longitudinal direction takenalong line 14B-14B of FIG. 14;

FIG. 15 illustrates winding circumferential “hoop” reinforcing fibersaround the in-progress balloon and mandrel in accordance with additionalembodiments;

FIG. 15A is an enlarged cross-sectional view of the in-progress balloonwall overlying the mandrel looking in the circumferential directiontaken along line 15A-15A of FIG. 15;

FIG. 15B is an enlarged cross-sectional view of the in-progress balloonwall overlying the mandrel looking in the longitudinal direction takenalong line 15B-15B of FIG. 15;

FIG. 16 illustrates applying a third coating layer over the in-progressballoon and mandrel in accordance with additional embodiments;

FIG. 16A is an enlarged cross-sectional view of the in-progress balloonwall overlying the mandrel looking in the circumferential directiontaken along line 16A-16A of FIG. 16;

FIG. 16B is an enlarged cross-sectional view of the in-progress balloonwall overlying the mandrel looking in the longitudinal direction takenalong line 16B-16B of FIG. 16;

FIG. 17 illustrates wrapping an outer layer over the in-progress balloonand mandrel in accordance with additional embodiments;

FIG. 17A is an enlarged cross-sectional view of the in-progress balloonwall overlying the mandrel looking in the circumferential directiontaken along line 17A-17A of FIG. 17;

FIG. 17B is an enlarged cross-sectional view of the in-progress balloonwall overlying the mandrel looking in the longitudinal direction takenalong line 17B-17B of FIG. 17;

FIG. 18 illustrates placing the final balloon lay-up and mandrel into adie prior to thermal welding in accordance with additional embodiments;

FIG. 19 show the die of FIG. 18 closed over the final balloon lay-up andmandrel prior to thermal welding;

FIG. 20 is a cross-sectional view taken in the direction of line 20-20of FIG. 19 showing the die, final balloon lay-up and mandrel beingheated in a oven in accordance with additional embodiments; and

FIG. 21 is a perspective view of the collapsed mandrel being removedfrom the finished medical balloon after thermal welding in accordancewith additional embodiments.

DETAILED DESCRIPTION

Referring now to the drawings, wherein like reference numbers are usedherein to designate like elements throughout, the various views andembodiments of a non-compliant medical balloon are illustrated anddescribed, and other possible embodiments are described. The figures arenot necessarily drawn to scale, and in some instances the drawings havebeen exaggerated and/or simplified in places for illustrative purposesonly. One of ordinary skill in the art will appreciate the many possibleapplications and variations based on the following examples of possibleembodiments.

Referring now to FIG. 1, there is illustrated a non-complaint medicalballoon in accordance with one aspect, shown in its fully inflatedstate. Balloon 100 includes a generally cylindrical barrel portion 102disposed between tapered cone portions 104 and cylindrical neck portions106 extending therefrom along a longitudinal axis 108. The outer surface110 of the cone portion 104 forms an angle 112 (the “cone angle”) withrespect to a longitudinal extension of the wall of the barrel portion102. Conventional non-compliant balloons are typically limited to coneangles in the range of about 12 degrees to 16 degrees in order tominimize bulging (when folded) due to the thickness of the cone walls.As described further herein, embodiments of the balloon 100 may have acone angle 112 in the range of 12 degrees to 22 degrees. In preferredembodiments, the cone angle 112 is in the range of 18 degrees to 22degrees, and in more preferred embodiments, the cone angle 112 is about20 degrees. The higher cone angle 112 results in shorter overall lengthfor the balloon for a given barrel length.

Referring now to FIG. 2, a balloon 100 is shown in cross-section toillustrate further its structure. The diameter of the barrel portion 102of the balloon ranges between a maximum size when inflated, denotedD_(I), and a minimum size when deflated and folded, denoted D_(D) (notshown). The diameter of the neck portion 106, denoted D_(N), stayssubstantially constant regardless of inflation state. In preferredembodiments, the deflated diameter D_(D) of the balloon is substantiallyequal to the neck diameter D_(N). The barrel portion 102 of the balloonhas a length, denoted L_(B), measured between cone portions 104. Theoverall length, denoted L_(O), is generally measured to the outer endsof the cone portions 104.

The walls of the balloon 100 include a barrel wall 114 having arelatively constant thickness, denoted T_(B), cone walls 116 having athickness ranging from a minimum, denoted T_(CMIN), to a maximum,denoted T_(CMAX), and neck walls 122 having a relatively constantthickness, denoted T_(N). In prior art non-compliant balloons, T_(CMIN)was often located near the barrel end 118 of the cone wall 116 andT_(CMAX) was often located near the neck-end 120. In the improvedballoons disclosed herein, T_(CMIN) and T_(CMAX) may be disposed atlocations other than those shown, and in some embodiments the wallthickness along the cone wall 116 may be essentially constant such thatT_(CMIN) and T_(CMAX) are approximately equal. In preferred embodiments,the cone walls 116 of balloon 100 have a relatively constant thicknesssuch that the difference between T_(CMAX) and T_(CMIN) is not greaterthan ±10% of T_(CMIN). More preferably, the difference between T_(CMAX)and T_(CMIN) is not greater than ±5% of T_(CMIN). In still furtherembodiments, the thickness of the barrel wall 114 and cone walls 116(collectively referred to as the “folding walls” since they must befolded when the balloon is in the deflated state to achieve the minimumdiameter D_(D)) are substantially equal such that the difference betweenwall thicknesses T_(B), T_(CMIN) and T_(CMAX) is not greater than ±10%of T_(B). More preferably, the maximum difference between the foldingwall thicknesses T_(B), T_(CMIN) and T_(CMAX) is not greater than ±5% ofT_(B).

Referring now to FIGS. 2A and 2B, enlarged cross-sections of the wall ofballoon 100 are shown to illustrate the structure further. Although theillustrated cross-sections are taken through the barrel wall 114, asfurther disclosed herein the wall structures in the barrel wall 114,cone walls 116 and neck walls 122 are substantially identical to oneanother and will therefore collectively be identified as balloon wall200. The balloon wall 200 has a composite structure including a firstlayer 201 of longitudinally-oriented reinforcing fibers 202 and secondlayer 203 of circumferentially- or “hoop-” oriented reinforcing fibers204 embedded in a matrix 206 of thermally-weldable polymer material. Thematrix 206 may be a single material or it may comprise multiple regionsof compatible thermally-weldable polymer material that have beenthermally welded into a continuous matrix. It will be appreciated thatthermal welding, wherein heat and pressure alone are used to form a bondbetween the materials being joined, is differentiated from adhesivebonding, wherein an adhesive material (e.g., epoxy, polyurethane, etc.)is introduced between the materials being joined. In the illustratedembodiment, the matrix material 206 comprises an inner region 208, afirst coating region 210, a sock region 212 (disposed primarily betweenthe longitudinal fibers 202), a second coating region 214, a thirdcoating region 216, a fourth coating region 218 and an outer region 220,all of which are compatible thermally-weldable materials. Preferably,the matrix 206 does not include any adhesive layers.

In one embodiment, the matrix 206 may be formed of thermally-weldablenylon (i.e., aliphatic polyamide) or polyamide blend. In anotherembodiment, the first coating region 210, the sock region 212, thesecond coating region 214, the third coating region 216 and the fourthcoating region 218 are formed of soluble nylon and the inner region 208and the outer region 220 are formed of a polyether block amide (PEBA), anylon-containing thermoplastic blend, having a durometer hardness in therange from about Shore D 25 to about Shore D 54. Since both materialscontain substantial parts nylon, they are thermal-welding compatible. Ina preferred embodiment, the first coating region 210, the sock region212, the second coating region 214, the third coating region 216 and thefourth coating region 218 are formed of soluble nylon and the innerregion 208 and the outer region 220 are formed of Type-5533 PEBAX® brandPEBA having a durometer hardness of about Shore D 55.

It will be appreciated that the thickness of the fibers and regions inFIGS. 2A and 2B are not necessarily shown to scale. Also, some of thematrix regions may not be present in every portion of the balloon wall200. For example, in some embodiments the second coating region 214 maybe disposed only in the cone walls 116 portion of the balloon wall.

The longitudinally-oriented reinforcing fibers 202 are substantiallyinelastic fibers oriented parallel or substantially parallel to oneanother and parallel within ±10 degrees to the balloon's longitudinalaxis 108. The circumferentially- or hoop-oriented reinforcing fibers 204are substantially inelastic fibers oriented parallel or substantiallyparallel to one another and perpendicular within ±10 degrees to thelongitudinally-oriented reinforcing fibers 202. The reinforcing fibers202 and 204 may be formed of a variety of inelastic materials,including, but not limited to, Kevlar, Vectran, Spectra, Dacron,Dyneema, Turlon (PBT), Zylon (PBO), polyimide (PIM) and other ultrahighmolecular weight polyethylenes, aramids, and the like. In oneembodiment, the longitudinal fibers 202 and the hoop fibers 204 may bearamid fibers, preferably multi-filament. In another embodiment, thelongitudinal fibers 202 and the hoop fibers 204 may be para-aramidfibers, multi-filament. In a preferred embodiment, the longitudinalfibers 202 and the hoop fibers 204 may be Technora® brandparaphenylene/3,4-oxydiphenylene/terephthalamide copolymer, preferablymulti-filament. The material of the reinforcing fibers 202 and 204 neednot be thermally-weldable since the fibers are encapsulated in thematrix 206, however, the fiber material must be thermally compatiblewith the matrix material. In this context, the term “thermallycompatible” is used to indicate that the material of the reinforcingfibers 202 and 204 can withstand the heat and temperatures required forthermal welding of the materials forming the matrix 206 without materialdegradation.

Referring still to FIGS. 2A and 2B, the longitudinal reinforcing fibers202 have a width 222 and a thickness 224, and the hoop reinforcingfibers 204 have a width 226 and a thickness 228. Preferably, thereinforcing fibers 202 and 204 are “flattened” to reduce the overallthickness of the balloon wall 200 while maintaining the samecross-sectional area. In some embodiments, the longitudinal fibers 202have a width-to-thickness ratio in the range from about 25:1 to about45:1, and in preferred embodiments, the longitudinal fibers 202 have awidth-to-thickness ratio in the range from about 30:1 to about 40:1. Insome embodiments, the hoop fibers 204 have a width-to-thickness ratio inthe range from about 25:1 to about 45:1, and in preferred embodiments,the hoop fibers 204 have a width-to-thickness ratio in the range fromabout 30:1 to about 40:1.

Although the balloon 100 may be constructed to any dimensions, balloonshaving a deflated diameter D_(D) in the range from about 4 French Units(i.e., about 0.053 inches or 1.35 millimeters) to about 12 French Units(i.e., about 0.158 inches or 4.0 millimeters) are particularly useful inthe fields of cardiology, radiology, orthopedics and urology. Producingsuch small diameter non-complaint balloons requires extremely thinballoon walls. In one embodiment, balloon 100 is a medical balloonhaving a deflated diameter D_(D) in the range of 4 to 12 French Unitsand a folding wall thickness (i.e., T_(B) and T_(CMAX)) in the range ofabout 0.001 inches to about 0.0023 inches (per wall). In anotherembodiment, balloon 100 is a medical balloon having a deflated diameterD_(D) in the range of 4 to 12 French Units and a folding wall thicknessin the range of about 0.0015 inches to about 0.0020 inches (per wall).In yet another embodiment, balloon 100 is a medical balloon having adeflated diameter D_(D) in the range of 4 to 6 French Units and afolding wall thickness in the range of about 0.001 inches to about0.0020 inches (per wall).

Referring now to FIGS. 3-22, details of the medical balloon 100 andmethods for manufacturing such balloons are disclosed. In someembodiments, all of the longitudinal reinforcing fibers 202 may beattached to the balloon structure as part of a pre-formed sheet called a“sock.” Use of this sock process may significantly simplify assembly ofthe balloon 100, reduce costs, improved quality and/or yield otherbenefits.

Referring first to FIG. 3, one method of construction of the balloon 100begins with formation of a removable semi-compliant mandrel. The mandrelbegins as a raw mandrel tube 300 comprising a tube of blow moldablematerial, such as polyethylene terephthalate (PET). The tube 300 has alongitudinal axis 302. For balloons in the 4 to 12 French Unit size, theraw mandrel tube 300 will typically have an outer diameter (O.D.) ofabout 0.05 inches to about 0.15 inches and a wall thickness of about0.010 inches to about 0.020 inches.

Referring now to FIG. 4, an inner sleeve 400 of balloon matrix materialis placed over the raw mandrel tube 300 prior to blow molding. The innersleeve 400 will not become part of the removable mandrel; rather, itwill become an integral part of the finished balloon, namely, the innerregion 208 of the matrix 206. Accordingly, the materials of the rawmandrel tube 300 and of the inner sleeve 400 must be selected such thatthey do not thermally weld or otherwise stick together during subsequentoperations as the balloon is constructed. For a mandrel formed of PET,the inner sleeve 400 may be formed of PEBA, such as Pebax®. For balloonsin the 4 to 12 French Unit size, inner sleeve 400 may be formed of PEBAhaving a thickness of about 0.004 inches to about 0.005 inches per wall(before blow molding).

Referring now to FIGS. 5, 5A and 5B, the raw mandrel tube 300 with theinner sleeve 400 in place is blow-molded using conventional techniquesto form a balloon-shaped semi-compliant mandrel 500 covered by aconformal layer 502 of material from the sleeve 400. The longitudinalaxis 302 of the raw mandrel tube 300 now becomes the longitudinal axisof the mandrel 500. The conformal layer 502 will ultimately become theinner region 208 of the balloon wall 200. As best seen in FIGS. 5A and5B, the walls of the mandrel 500 and the conformal layer 502 aregenerally uniform when viewed in cross-section in either thecircumferential or longitudinal direction. When constructing balloons100 in the 4 to 12 French Unit size, the wall thickness of the mandrel500 after blow-molding may be within the range of about 0.005 inches toabout 0.0015 inches along the barrel, and the thickness (per wall) ofthe conformal layer 502 after blow-molding may be in the range of about0.0003 inches to about 0.0006 inches. The shape of the mandrel 500 ismaintained during the balloon-construction process by internallypressurizing the mandrel to a predetermined pressure.

Referring now to FIG. 6, the inelastic fiber material used to make thereinforcing fibers 202 and 204 of balloon 100 may originally be providedin the form of a bundle or “tow” 600 of individual filaments 602. Anadhesive or gel 604 may be included between the filaments 602 to helpmaintain the shape of the tow 600. The tow may have a generally circularcross-section with a width 606 and thickness 608 substantially equal toone another and substantially greater than the thickness 610 of anindividual filament 602.

Referring now to FIG. 7, there is illustrated a tow of inelastic fibermaterial that has been modified to form reinforcing fibers 202, 204having a flattened cross-section. In preferred embodiments, thethickness 224, 228 of the fibers 202, 204, respectively, may be withinthe range of about 1 to 2 times the thickness 610 of an individualfilament 602. For example, Technora® brand para-aramid fiber having anoriginal tow thickness 608 of about 0.003 inches and a filamentthickness 610 of about 0.0005 inches may be flattened to formreinforcing fibers 202, 204 having a thickness 224, 228 of about 0.0005inches and a width 222, 226 of about 0.015 inches.

Referring now to FIG. 8, one process for forming the flattenedreinforcing fibers 202, 204 is illustrated. The original tow 600 ofinelastic fiber is unreeled from a supply drum 800 and squeezed betweenone or more sets of closely spaced-apart rollers 802. A solvent orsolvent-based adhesive may be applied to the tow 600 at awetting-station 804 to remove or soften the original adhesive/gel 604and facilitate rearrangement of the filaments 602 within the tow. Thespacing between the final set of rollers 802 controls the thickness ofthe reinforcing fiber 202, 204. After leaving the final set of rollers802, the fibers 202, 204 may be dried, if necessary, and then usedimmediately or stored for later processing.

Referring still to FIG. 8, one process for forming the so-called sock(i.e., the pre-formed sheet incorporating the longitudinal reinforcingfibers 202) begins by winding the flattened fiber 202 onto a sock drum806 at a predetermined pitch (i.e., distance between successive fiberpositions) 808. In the illustrated embodiment, the flattened fiber 202is wound onto the sock drum 806 directly after leaving the flatteningrollers 802, however, in other embodiments the fiber 202 may beprocessed earlier and provided from a storage roll (not shown). Thepitch 808 between successive winds of fiber 202 may be produced bymoving the sock drum 806 laterally (denoted by arrow 810) while windingor by moving the fiber feed laterally across the sock drum whilewinding. In some embodiments, the pitch 808 is selected to provide aspacing (i.e., spacing=pitch minus fiber width) between winds that isless than one fiber width 222. In preferred embodiments, the pitch 808is selected to provide spacing between winds that is less than 50% ofthe fiber width 222, and in more preferred embodiments, the pitch isselected to provide spacing between winds that is less than 25% of thelongitudinal fiber width. For example, in one embodiment havinglongitudinal fibers 202 with width 222 of about 0.015 inches, the pitch808 is about 66 TPI (threads per inch), leaving a space of only about0.0002 inches between fibers.

Prior to winding the longitudinal reinforcing fibers 202 onto the sockdrum 806, a layer of anti-stick/protective material 812 may be appliedto the drum surface. In one embodiment, the anti-stick/protectivematerials 812 is a layer of Teflon® brand tape wrapped around the drum806. The anti-stick/protective material 812 protects the fibers 202 fromthe drum and facilitates release of the sock from the drum afterprocessing.

Referring now to FIG. 9, after winding the reinforcing fibers 202 ontothe drum 806, a sock coating 900 of thermally-weldable polymer material902 may be applied across the fibers and surface of the drum. The sockcoating 900 is preferably applied by spraying, but may be applied bybrushing, dipping or other means. The sock coating 900 will ultimatelybecome the sock region 212 of the matrix 206; therefore, it must becompatible for thermal-welding to the other materials in the matrix. Inone embodiment, the sock coating 900 may be formed of a soluble nylonmaterial having a thickness of about 0.0003 inches. In an alternativeembodiment (not shown) the sock coating 900 is applied directly to thesurface of the sock drum 806 (or, if present, to theanti-stick/protective material 812) before winding on the reinforcingfibers 202. In one such alternative embodiment, the sock coating 900 maybe formed of a: soluble nylon material having a thickness of about0.0003 inches.

Referring now to FIG. 10, after applying the sock coating 900 to thelongitudinal fibers 202 (or vice-versa) and allowing it to dry, theresulting sock sheet 1000 is cut and removed from the drum 806. The socksheet 1000 now comprises a plurality of substantially parallelreinforcing fibers 202 affixed to a film of thermally-weldable polymermaterial 902 (from the sock coating 900).

Referring now to FIG. 11, the sock sheet 1000 is pressed and heated tosmooth its surfaces and firmly embed the reinforcing fibers 202 into thethermally-weldable matrix material 902. In one embodiment, the socksheet 1000 is placed between two flat steel sheets 1100, clampedtogether, and heated in an oven (not shown). In another embodiment,wherein the reinforcing fibers 202 are Technora® brand para-aramidfibers approximately 0.0005 inches thick, and the thermally-weldablematerial 902 is nylon, the sock sheet is heated between flat steelsheets at 250 degrees F. for a period within the range of about 20 to 30minutes. During the pressing/heating procedure, the matrix material 902may plastically deform such that, after cooling, the sheet is perfectlysmooth and has the thickness of the reinforcing fibers 202.

Referring now to FIGS. 12, 13, and 13A-F, the finished sock sheet 1000is next patterned and cut to shape. A flat pattern 1200 may be createdcorresponding to the outer wall of the balloon 100, wherein the patternrepresents the three-dimensional outer surface of the balloon that hasbeen cut along lines parallel to the longitudinal axis 108 and“unfolded” into a two-dimensional (i.e., flat) surface. The pattern 1200will have a pattern axis 1202 corresponding to a line on the surface ofthe balloon 100 that is parallel to the longitudinal axis 108. In theillustrated embodiment, the pattern 1200 may correspond to the entireouter wall of the balloon 100 (including the barrel wall 114, cone walls116 and neck walls 122). In another embodiment, the pattern 1200 maycorrespond to selected portions of the outer wall of the balloon 100. Inpreferred embodiments, the pattern 1200 will correspond to portions ofthe surface of the balloon extending longitudinally along the entirelength of the balloon, i.e., from the outer end of one neck to the outerend of the opposite neck.

Referring now specifically to FIG. 12, for purposes of illustration thereinforcing fibers 202 may be shown in FIG. 12 as having an abbreviatedlength in order to more clearly show the pattern 1200, however it willbe understood that the fibers 202 may actually run across the entirelength of the sock sheet 1000 as shown in FIG. 11. The pattern 1200 maybe superimposed on the sock sheet 1000 with the pattern axis 1202oriented substantially parallel to the reinforcing fibers 202. This mayensure that the longitudinal reinforcing fibers 202 run substantiallyparallel to the longitudinal axis 108 in the finished balloon 100. Thepattern 1200 may then be cut out of the sock sheet 1000 to form thefinal patterned sock 1300. In one embodiment, the pattern 1200 may betransferred to the surface of the sock sheet 1000 (e.g., by printing)and the patterned sock 1300 may be cut out by hand (e.g., by knife,scissors, etc.). In another embodiment, the pattern 1200 may beincorporated into the shape of a cutting tool (e.g., a cutting die orcutting punch) and the patterned sock 1300 may be cut from the properlyoriented sock sheet 1000 by an automated cutting apparatus (e.g., a diecutting machine) using the cutting tool. In yet another embodiment, thepattern 1200 may be incorporated into a computer program or set of CNCinstructions and the patterned sock 1300 may be cut from the properlyoriented sock sheet 1000 by a computer-controlled/CNC cutting apparatus,e.g., a laser cutter 1204 (shown in FIG. 12), a water jet cutter ornumerically-controlled knife.

Referring now specifically to FIG. 13, the finished patterned sock 1300may include barrel, cone and neck portions 1302, 1304 and 1306,respectively corresponding to the barrel, cone and neck portions 102,104 and 106 of the finished balloon 100. In the finished patterned sock1300, selected reinforcing fibers 202 may extend continuously from onelongitudinal end of the patterned sock to the opposite longitudinal end.For example, in the embodiment illustrated in FIG. 13, reinforcing fiber202 a extends continuously from neck portion 1306 a at one longitudinalend of the patterned sock to neck portion 1306 b at the oppositelongitudinal end.

Referring now specifically to FIG. 13A, an enlarged portion of thepatterned sock 1300 is shown to better illustrate the pattern of thereinforcing fibers 202 within the sock. It will be understood thatoutline of the sock shown in FIG. 13A is for purposes of illustrationand is not intended to show the exact shape necessary to cover theballoon shown in FIG. 1. As previously described, the fibers 202 of thepatterned sock 1300 may run substantially parallel to one another andsubstantially parallel to the sock axis 1202 that may be aligned withthe longitudinal axis 108 of the balloon. The fibers 202 in the sock mayhave a pattern of different lengths such that the fibers may be dividedinto a first group and a second group based on length. The first groupmay be termed the “neck group” (denoted by reference number 1308 in FIG.13A) and the second group may be termed the “cone group” (denoted byreference number 1310).

Each fiber of the neck group 1308 begins in the neck wall portion 1306at one end of the sock, extends continuously in the longitudinaldirection and terminates in the neck wall portion at the opposite end ofthe sock. The fibers denoted 202 b, 202 c, 202 d and 202 e are examplesof fibers in the neck group 1308. Substantially all of the fibers 202 inthe neck group 1308 have a generally uniform length.

Each fiber of the cone group 1310 begins in the cone wall portion 1304at one end of the sock, extends continuously in the longitudinaldirection and terminates in the cone wall portion at the opposite end ofthe sock. The fibers denoted 202 f, 202 g, 202 h and 202 i are examplesof fibers in the cone group 1310. In contrast to the previous group, thelength of the fibers 202 of the cone group 1310 varies progressively inaccordance to their proximity to the fibers of the neck group 1308. Thefibers of the cone group closer to the fibers of the neck group arelonger than the fibers of the cone group further from the fibers of theneck group. Accordingly, fiber 202 f, which is closest to the neck group1308, is the longest of the example fibers, while fiber 202 h, which isfarthest from the neck group, is the shortest of the example fibers.Fiber 202 g, disposed between fibers 202 f and 202 h, has anintermediate length. Fiber 202 i has a length approximately equal tothat of fiber 202 g, because each is approximately the same distancefrom a neck group 1308.

Turning to FIG. 13B, in an alternative embodiment, a sock sheet 1320 maybe reinforced by weaving fibers 1322 into a woven textile material 1324.The woven textile material 1324 has a structure wherein fibers orfilaments are interlaced. Fibers 1322 may be flattened prior to weavingas described above, or the woven textile material 1324 may be pressed,for example between rollers to achieve the desired thickness. In thisvariation, woven textile material 1324 may be coated with athermally-weldable polymer material 1326, as described in connectionwith FIG. 9. After the coating has been applied, the sock sheet 1320 maybe clamped between plates and heated to embed the fibers 1322 within thethermally-weldable polymer 1326 and produce a sheet 1320 having smoothsurfaces. Alternatively, a film formed from a thermally-weldable polymermaterial may be placed over woven textile material 1324 prior to heatingto form a sock sheet 1320. Fibers 1322 may form angles (denoted “A”) atthe intersections thereof that remain constant when a balloonincorporating sock material 1320 is inflated and deflated.

After embedding, the finished sock sheet 1320 formed using woven textilematerial 1324 may then be patterned and cut to shape as described above.For purposes of illustration, the weave of textile material 1324 isshown with a high porosity, i.e., a relatively large amount of openspace between fibers 1322. Other woven textile fabrics having greater orlesser porosities, including those having a very tight weave withessentially no porosity may be used in other embodiments.

FIG. 13C illustrates another alternative embodiment, wherein areinforced sock sheet 1328 may be reinforced by braiding fibers 1330into a braided textile fabric 1332. A braided fabric 1332 employs afiber architecture in which three or more fibers are intertwined in sucha way that no two fibers are twisted exclusively around one another.Since all of the fibers 1332 within a braided structure are continuousand mechanically locked, a braid has a natural mechanism that evenlydistributes load throughout the structure. Braided textile fabric 1332is formed from fibers 1330 that may be flattened before braiding.Alternatively, braided textile material 1332 may be otherwise processedto achieve the desired thickness. Braided textile material 1332 may becoated with a thermally-weldable polymer material 1326 and heated asdescribed above to embed fibers 1330 within the thermally-weldablepolymer to produce a sock sheet 1328 having uniform smooth surfaces.Alternatively, a film formed from a thermally-weldable polymer material1326 may be placed over braided textile material 1332 prior to heatingto form a sock sheet 1328. The finished sock sheet 1328 may then bepatterned and cut to shape. After fibers 1330 have been embedded in thethermally-weldable polymer 1326, the angles (denoted “A”) between thefibers preferentially remain constant when a balloon incorporating socksheet 1328 is inflated and deflated.

FIGS. 13D and 13E illustrate additional embodiments, wherein reinforcedsock sheets 1334 and 1344 are reinforced by knitted textile material1336 and non-woven textile material 1346, respectively. A knittedtextile fabric is produced by intertwining fibers 1338 in a series ofinterconnected loops 1340 rather than by weaving. In this fashion, theloops 1340 of fibers 1338 are mechanically interlocked. A weft-knittedstructure consists of horizontal, parallel courses of fibers andrequires only a single fiber 1338. Alternatively, warp knitting requiresone fiber 1338 for every stitch in the course, or horizontal row; thesefibers make vertical parallel wales. In contrast, non-woven textilefabrics 1346 are typically made from randomly-oriented fibers that areneither woven nor knitted. The fibers 1348 in non-woven fabricstypically have a web structure in which small fibers or filaments areheld together by inter-fiber friction (e.g., matting), thermal binding(e.g., with a meltable binder) or chemical adhesion.

Knitted textile material 1336 or non-woven textile material 1346 may beembedded in a thermally-weldable polymer 1326 as described above, cutand patterned to form a patterned sock material 1334 or 1344 similar tothat shown in FIG. 13. In the case of the non-woven textile fabric 1346,the fibers 1348 may be randomly oriented, chopped fibers of the same orvarying lengths that form random angles (denoted “A”) at each fiberintersection. After the knitted fiber loops 1340 or non-woven fibers1348 are embedded in the thermally-weldable polymer 1326, the relativepositions of the loops 1340 or angles A between fibers preferablyremains constant when a balloon incorporating sock sheet 1334 or 1344 isinflated and deflated.

The textile fabrics illustrated in FIGS. 13B-13E may be formed from avariety of substantially inelastic polymers. For example, Kevlar,Vectran, Spectra, Dacron, Dyneema, Turlon (PBT), Zylon (PBO), polyimide(PIM) and other ultrahigh molecular weight polyethylenes, aramids, andsimilar polymers may be used to manufacture the fibers.

Referring now to FIG. 13F, in another variation, multiple textilereinforcing layers may be used to form a patterned sock 1350. In theillustrated embodiment, patterned sock 1350 is formed from a firstnon-woven textile layer 1352 having randomly oriented fibers 1354 and asecond textile layer 1356 formed from woven fibers 1358. For purposes ofillustration, portions of the sock 1350 are broken away in FIG. 13F toshow both reinforcing layers 1352 and 1356. One or both of textilelayers 1352 and 1356 may be coated with a thermally-weldable polymermaterial 1360, or pressed together and heated to embed fibers 1354 and1358 in a continuous polymer matrix. In other embodiments, layers ofknitted, braided, woven, non-woven and patterned fabrics textiles andfibers may be combined to form patterned sock sheets.

Referring now to FIGS. 14, 14A and 14B, the patterned sock 1300 (oralternatively, socks 1320, 1328, 1334, 1344 or 1350) may be affixed overthe illustrated balloon lay-up 1400, which now comprises the conformallayer 502 covering the removable semi-compliant mandrel 500 (as seen inFIG. 5). The size and shape of the mandrel 500 is preserved duringprocessing by maintaining a predetermined internal pressure P₁ via thetube 300. The patterned sock 1300 may be oriented such that thereinforcing fibers 202 are oriented parallel or substantially parallelto the longitudinal axis 302 of the mandrel 500 (which corresponds atthis point to the longitudinal axis 108 of the final balloon 100). Insome embodiments, the reinforcing fibers 202 are oriented within ±10degrees of parallel to the longitudinal axis 302. In some embodiments, aone-piece patterned sock 1300 may be “rolled” (denoted by arrow 1401)onto the conformal layer 502 so as to cover the entire surface.Preferably, no adhesive materials are used to affix the patterned sock1300 to the conformal layer 502.

The patterned sock 1300 will ultimately become the first layer 201 oflongitudinally-oriented reinforcing fibers in the finished balloon 100.Embodiments in which the fibers 202 in the sock 1300 have a particularpattern may have a substantially similar pattern in the fibers of thefirst fiber layer 201 in the finished balloon 100. Embodiments in whichthe fibers 202 in the sock 1300 have a pattern of different lengths suchthat the fibers may be divided into a first group and a second groupbased on length may have a substantially similar pattern in the fibersof the first fiber layer 201 in the finished balloon 100. Thethermally-weldable material in the sock sheet will become the sockregion 212 of the matrix 206.

To facilitate attachment of the patterned sock 1300 to the conformallayer 502, in some embodiments a solvent compatible with thethermally-weldable material 902 of the sock sheet may be applied to“tackify” (i.e., to make slightly sticky or tacky) the inside surface ofthe patterned sock 1300. In other embodiments, a first coating 1402 ofthermally-weldable material may be applied over the conformal layer 502prior to affixing the patterned sock 1300. The first coating 1402 (ifpresent) is preferably applied by spraying, but may be applied bybrushing, dipping or other means. The first coating 1402 will ultimatelybecome the first coating region 210 of the matrix 206, therefore it mustbe compatible for thermal-welding to the other materials in the matrix.In one embodiment the first coating 1402 may be formed of a solublenylon material having a thickness of about 0.0003 inches. Such a firstcoating 1402 may be thermal-welding compatible with a conformal layer502 when formed of PEBA such as Pebax®. It will be appreciated that thepatterned sock 1300 may not be welded or permanently joined to theconformal layer 502 (or first coating 1402) at this time. It is onlynecessary that the patterned sock 1300 be affixed well enough to stay inposition during further processing.

Referring now specifically to FIGS. 14A and 14B, after affixing thepatterned sock 1300 over the conformal layer 502, the in-progress wall1404 of the balloon 100 is illustrated on the outer surface of themandrel 500. In the embodiment illustrated, the first coating 1402 hasbeen applied as previously described.

Referring now to FIGS. 15, 15A and 15B, the hoop reinforcing fibers 204may be affixed over the illustrated balloon lay-up 1500, which nowincludes the patterned sock 1300 with longitudinal reinforcing fibers202. The balloon lay-up 1500 is supported by the underlying mandrel 500,which remains pressurized at the predetermined internal pressure P₁ tomaintain its size and shape. The flattened hoop reinforcing fibers 204may be wound circumferentially around the balloon lay-up 1500 at apredetermined pitch 1504 such that successive winds are orientedparallel or substantially parallel to one another and perpendicular orsubstantially perpendicular to the longitudinally-oriented reinforcingfibers 202. In some embodiments, the hoop fibers 204 are wound within±10 degrees of perpendicular to the longitudinal reinforcing fibers 202

The flattened hoop fibers 204 may be supplied from a storage drum 1506or other source. In preferred embodiments, the fibers 204 may be woundcontinuously around the balloon lay-up 1500 from one neck to theopposite neck. In the illustrated embodiment, the circumferentialwinding (denoted by arrow 1502) is accomplished by revolving the storagedrum 1506 around the balloon lay-up 1500, however in other embodimentsthe balloon lay-up and mandrel 500 may be rotated. In some embodiments,the hoop pitch 1504 is selected to provide a spacing between hoop windsthat is less than one hoop fiber width 226. In preferred embodiments,the pitch 1504 is selected to provide spacing between hoop winds that isless than 50% of the hoop fiber width 226, and in more preferredembodiments, the pitch is selected to provide spacing between hoop windsthat is less than 25% of the hoop fiber width. For example, in oneembodiment having hoop fibers 204 with width 226 of about 0.015 inches,the pitch 1504 is about 66 TPI (threads per inch), leaving a space ofonly about 0.0002 inches between hoop fibers.

Prior to winding the hoop reinforcing fibers 204 onto the balloon lay-up1500, a second coating 1508 of thermally-weldable matrix material may beapplied to the surface of the balloon lay-up to facilitate retention ofthe hoop fibers. In some embodiments, the second coating 1508 is appliedonly to the surface of the cone portions 104, since the tendency for thefibers 204 to slip is greatest on the angled surfaces of the cones. Thesecond coating 1508 (if present) is preferably applied by spraying, butmay be applied by brushing, dipping or other means. The second coating1508 will ultimately become the second coating region 214 of the matrix206, therefore it must be compatible for thermal-welding to the othermaterials in the matrix. In one embodiment, the second coating 1508 maybe formed of a soluble nylon material having a thickness of about 0.0003inches. Such a second coating 1508 may be thermal-welding compatiblewith the first coating 1402 when formed of soluble nylon and/or theconformal layer 502 when formed of PEBA such as Pebax®. It will beappreciated that the patterned sock hoop fibers 204 may not be welded orpermanently joined to the balloon lay-up at this time. It is onlynecessary that the hoop fibers 204 be affixed firmly enough to stay inposition during further processing.

Referring now specifically to FIGS. 15A and 15B, after affixing the hoopreinforcing fibers, the in-progress wall 1510 of the balloon 100 isillustrated on the outer surface of the mandrel 500. In the embodimentillustrated, the second coating 1508 has been applied as previouslydescribed.

Referring now to FIGS. 16, 16A and 16B, a third coating 1602 may beapplied to the surface of the illustrated balloon lay-up 1600, which nowincludes both the hoop (i.e., circumferential) reinforcing fibers 204and the longitudinal reinforcing fibers 202. The balloon lay-up 1600 issupported by the underlying mandrel 500, which remains pressurized atthe predetermined internal pressure P₁ to maintain its size and shape.The third coating 1602 may facilitate holding the hoop fibers 204 inposition and smoothing the surface of the balloon. In some embodiments,the third coating 1602 is applied to the entire surface of the balloonlay-up 1600. The third coating 1602 is preferably applied by spraying,but may be applied by brushing, dipping or other means. The thirdcoating 1602 will ultimately become the third coating region 216 of thematrix 206, therefore it must be compatible for thermal-welding to theother materials in the matrix. In one embodiment, the third coating 1602may be formed of a soluble nylon material having a thickness of about0.0003 inches. Such a third coating 1602 may be thermal-weldingcompatible with the second coating 1508 (where present) when formed ofnylon and with the thermally-weldable material 902 of the underlyingsock sheet 1000 when formed of nylon.

Referring now specifically to FIGS. 16A and 16B, after applying thethird coating 1602, the in-progress wall 1604 of the balloon 100 isillustrated on the outer surface of the mandrel 500.

Referring now to FIGS. 17, 17A and 17B, an outer layer 1702 may beaffixed over the illustrated balloon lay-up 1700, which now includes thethird coating 1602. The balloon lay-up 1700 is supported by theunderlying mandrel 500, which remains pressurized at the predeterminedinternal pressure P₁ to maintain its size and shape. The outer layer1702 may provide additional material to increase the puncture-resistanceand surface smoothness of the balloon 100. In some embodiments, theouter layer 1702 may comprise a thermally-weldable polymer material. Theouter layer 1702 preferably comprises the same material as the balloonmatrix 206 or material compatible with the material of balloon matrix.Preferably the outer layer 1702 is formed from the same material as theconformal layer 502. Thus, when the conformal layer 502 is formed fromPEBA thermoplastic elastomer, the outer layer 1702 is preferably formedfrom the same material. In a preferred embodiment, the outer layer maybe formed of PEBA, e.g., Pebax®.

In the illustrated embodiment, the outer layer 1702 may comprise athermally-weldable polymer tape or film 1704 that may be wrappedcircumferentially around the balloon lay-up 1700 at a predeterminedpitch 1706. In one embodiment, the pitch 1706 may be smaller than thewidth of the tape 1704 such that successive winds may overlap. The outerlayer tape 1704 may be supplied from a storage drum 1708 or othersource. In preferred embodiments, the tape 1704 may be woundcontinuously around the balloon lay-up 1700 from one neck to theopposite neck. In the illustrated embodiment, the circumferentialwinding (denoted by arrow 1710) is accomplished by revolving the storagedrum 1708 around the balloon lay-up 1700, however in other embodimentsthe balloon lay-up and mandrel 500 may be rotated. For balloons 100 inthe 4 to 12 French Unit size, the outer layer 1702 may be formed ofPEBA, e.g., Pebax®, having a thickness of about 0.0003 inches. Suchsmall thickness may be obtained by stretching PEBA tape having anoriginal thickness of about 0.0005 inches.

Prior to affixing the outer layer 1702 onto the balloon lay-up 1700, afourth coating 1712 of thermally-weldable matrix material may be appliedto the underside surface of the outer layer material 1704 to facilitateits retention. The fourth coating 1712 is preferably applied byspraying, but may be applied by brushing, dipping or other means. Thefourth coating 1712 will ultimately become the fourth coating region 218of the matrix 206, therefore it must be compatible for thermal-weldingto the other materials in the matrix. In one embodiment, the fourthcoating 1712 may be formed of a soluble nylon material having athickness of about 0.0003 inches. Such a fourth coating 1712 may bethermal-welding compatible with the third coating 1602 when formed ofnylon and with the outer layer 1702 when formed of PEBA, e.g., Pebax®.It will be appreciated that the outer layer 1702 may not be welded orpermanently joined to the balloon lay-up at this time. It is onlynecessary that the outer layer 1702 be affixed firmly enough to stay inposition during further processing.

Referring now specifically to FIGS. 17A and 17B, after affixing theouter layer 1702, the final lay-up wall 1714 of the balloon 100 isillustrated on the outer surface of the mandrel 500. In the embodimentillustrated, the fourth coating 1712 has been applied as previouslydescribed. The overlapping of the tape 1704 is shown at arrow 1716.

Referring now to FIGS. 18, 19 and 20, there is illustrated the thermalwelding of the final balloon lay-up 1800 following application of theouter layer 1702 described above. Referring first to FIG. 18, the finallay-up 1800 (with the mandrel 500 still inside) may be placed inside adie 1802 having a balloon-shaped cavity 1804. Passages 1806 may beprovided in die 1802 so that the mandrel tube 300 may extend outside toallow pressurization while the lay-up is in the die.

Referring now to FIG. 19, after the final balloon lay-up 1800 is placedin the die cavity 1804, the die 1802 may be closed and secured. Next,heat and pressure are applied to thermally weld the components of theballoon lay-up into the final balloon 100.

Referring now to FIG. 20, in one embodiment the die 1802 containing thefinal balloon lay-up 1800 is placed inside an oven 2000 for heating (forpurposes of illustration, the wall of the final lay-up 1800 is shown insimplified form in FIG. 20). In other embodiments, a die having integralheating may be used. While inside the die, the mandrel 500 may beinternally pressurized to a predetermined pressure P₂. Since the mandrel500 is semi-compliant, the internal pressure P₂ will force the mandrelwalls outward, pressing each wall 1714 of the final lay-up 1800 againstthe heated walls of the die cavity 1804. In some embodiments, the die1802 may be heated before the mandrel 500 is pressurized. In otherembodiments, the mandrel 500 may be pressurized before the die 1802 isheated. In still other embodiments, the heating of the die and thepressurization of the mandrel 500 may occur simultaneously.Predetermined conditions of heat and pressure maintained inside the die1820 for a predetermined time period may weld together thethermally-weldable components of the final lay-up wall 1714 (FIGS. 17Aand 17B), thereby forming the finished balloon wall 200 (FIGS. 2A and2B). In one embodiment, a final balloon lay-up 1800 comprisingreinforcing fibers 202, 204 made of Technora® brand para-aramid layeredwith nylon and Pebax® brand PEBA component layers may be thermallywelded by heating the die 1802 to about 300 degrees F., pressurizing themandrel 500 to about 150 psi, and maintaining these conditions for aperiod of about 2 minutes.

During the thermal welding process, the thermally-weldable materials inthe wall 1714 of the final lay-up 1800 may fuse to one another forming acontinuous matrix 206 of the finished balloon wall 200 (FIGS. 2A and2B). In preferred embodiments, the matrix 206 may be continuous and freeof adhesive materials. In some embodiments, the thermally-weldablematerials in the wall 1714 of the final lay-up may plastically deformunder heat and pressure to fill any voids (e.g., in-between and aroundthe reinforcing fibers) such that the reinforcing fibers 202 and 204 arefully encapsulated by the matrix 206 in the finished balloon 100. Insome embodiments, the thermally-weldable materials in the wall 1714 ofthe final lay-up may plastically deform under heat and pressure toeven-out surface irregularities (e.g., the tape overlap 1716) such thatthe outer surface 230 of the finished balloon wall 200 is very smooth.In some embodiments, the thermally-weldable materials in the wall 1714of the final lay-up may weld together, plastically deform and/or becompressed under heat and pressure such that the overall thickness ofthe finished balloon wall 200 is significantly less than the thicknessof the wall 1714.

After thermal welding is complete, the die 1802 may be cooled, thepressure in the mandrel 500 may be reduced, and the balloon 100 (stilloverlying the mandrel 500) may be removed from the die cavity. The wallsof the mandrel 500 mandrel walls may then be collapsed by releasing theinternal pressure or applying a partial vacuum via the tube 300.

Referring now to FIG. 21, after collapsing the walls of the mandrel 500inside the balloon 100, the mandrel itself may be removed from theballoon by pulling it through the neck 106 of the balloon by means oftube 300. The balloon 100 is now complete (FIGS. 1 and 2) and ready forinspection and testing or further processing, e.g., attachment to acatheter.

It will be appreciated by those skilled in the art having the benefit ofthis disclosure that this non-compliant medical balloon may provideimproved flexibility, simplified assembly, reduced folding wallthickness and/or more uniform wall thicknesses. It should be understoodthat the drawings and detailed description herein are to be regarded inan illustrative rather than a restrictive manner, and are not intendedto be limiting to the particular forms and examples disclosed. On thecontrary, included are any further modifications, changes,rearrangements, substitutions, alternatives, design choices, andembodiments apparent to those of ordinary skill in the art, withoutdeparting from the spirit and scope hereof, as defined by the followingclaims. Thus, it is intended that the following claims be interpreted toembrace all such further modifications, changes, rearrangements,substitutions, alternatives, design choices, and embodiments.

What is claimed is:
 1. A medical balloon, comprising: a first fiberlayer and a second fiber layer embedded in a continuous matrix ofthermally-weldable polymer material; wherein the first fiber layer, thesecond fiber layer, and the polymer material are thermally welded toform the continuous matrix.
 2. The balloon according to claim 1, whereinthe first fiber layer comprises a plurality of fibers runningsubstantially parallel to one another and substantially parallel to alongitudinal axis of the balloon, the fibers of the first fiber layerhaving a pattern of different lengths and being divisible into a firstgroup and a second group based on length.
 3. The balloon according toclaim 2, wherein the second fiber layer includes at least one fiberwound circumferentially around and at least partially along thelongitudinal axis of the balloon.
 4. The balloon according to claim 1,wherein the thermally-weldable polymer material of the continuous matrixincludes nylon and polyether block amide (PEBA).
 5. The balloonaccording to claim 4, wherein the continuous matrix does not include anynon-thermally-weldable materials.
 6. The balloon according to claim 1,wherein the continuous matrix does not include anynon-thermally-weldable adhesive materials.
 7. The balloon according toclaim 1, wherein the first fiber layer comprises fibers that are eachsubstantially equally spaced from one another, and the second fiberlayer comprises at least one fiber substantially equally spaced in eachcircumferential wind.
 8. The balloon according to claim 7, wherein thefirst fiber layer underlies the second fiber layer.
 9. The balloonaccording to claim 1, further including an inner layer of thermallyweldable material contacting at least the plurality of fibers of thefirst layer.
 10. The balloon according to claim 9, further including aremoveable mandrel supporting the inner layer.
 11. The balloon accordingto claim 10, wherein the mandrel comprises a non-thermally weldablematerial.
 12. A medical balloon, comprising: a first fiber layer and asecond fiber layer, said first and second fiber layers embedded in acontinuous matrix of thermally-weldable polymer material; wherein thefirst fiber layer, the second fiber layer, and the polymer material arethermally welded to form the continuous matrix without an adhesivetherein.
 13. The balloon according to claim 12, wherein the first andsecond fiber layers embedded in the continuous matrix ofthermally-weldable polymer materials define a barrel wall, cone wallsand neck walls of the balloon.
 14. The balloon according to claim 13,wherein the fibers of the first fiber layer have a pattern of differentlengths and are divisible into a first group and a second group based onlength.
 15. The balloon according to claim 14, wherein each fiber of thefirst group begins the neck wall at one end of the balloon, extendslongitudinally and terminates in the neck wall at the opposite end ofthe balloon; and each fiber of the second group begins in the cone wallat one end of the balloon, extends longitudinally and terminates in thecone wall at the opposite end of the balloon.
 16. The balloon accordingto claim 15, wherein the length of the fibers of the second group variesprogressively in accordance to their proximity to the fibers of thefirst group, the fibers of the second group closest to the fibers of thefirst group being longer than the fibers of the second group furtherfrom the fibers of the first group.
 17. The balloon according to claim12, further including a removable mandrel for supporting the inner layerof thermally weldable material.
 18. The balloon according to claim 17,wherein the mandrel comprises a non-thermally weldable material.
 19. Amedical balloon having a longitudinal axis, comprising: a first fiberlayer and a second fiber layer embedded in a continuous matrix ofthermally-welded polymer material; wherein the first fiber layercomprises a plurality of fibers extending along the longitudinal axishaving different lengths and divided into a first group and a secondgroup based on length.
 20. The balloon according to claim 19, whereineach fiber of the first group begins in a neck wall at one end of theballoon, extends longitudinally and terminates in a neck wall at theopposite end of the balloon; each fiber of the second group begins in acone wall at one end of the balloon, extends longitudinally andterminates in a cone wall at the opposite end of the balloon; and thesecond fiber layer comprises at least one fiber wound circumferentiallyaround and along the longitudinal axis of the balloon.